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It sounds to me like this will not work if I actually power down my device before the attacker gets their hands on it, is that correct? (I tend to power down my
by MBlume 11y ago
It sounds to me like this will not work if I actually power down my device before the attacker gets their hands on it, is that correct? (I tend to power down my phone before going through TSA lines, for example)
- rogeryu 11y agoIt appears to me that RAM content is not cleared completely when you power down the device. Encryption keys may still be present in memory So powered down, you freeze the phone, which keeps the RAM at its current state, and then with some magic tricks you can read that memory. So powering down is not enough. In the future I guess powering down needs an extra action, wiping memory first.
- andrewaylett 11y agoIn this particular case, the freezing happens while the power is on with the data you want in RAM. If the phone has already been switched off without freezing, it will lose the contents of its RAM pretty quickly.
- chrisfosterelli 11y agoYes, cold boot attacks only work if they can get to the machine before it is turned off. If it has been turned off while warm, the RAM contents very very quickly degrade. This is pretty interesting since most people don't get to turn their phone off when it is stolen. In the case of the TSA you're safe, though. Fun fact: This is why during raids against cyber criminals reports claim they often dive for their computer to try and turn it off before being restrained. Police can do the same thing with liquid nitrogen and a desktop machine.
- Johnny555 11y agoSounds like a coil of heating wire around the chips that's triggered by cryogenic temperatures entering the computer case (or the PC's case being opened) would keep their secrets safe. I.e. if triggered, motherboard power is cut off, and the LiIon battery dumps power through the heating wire and quickly bakes the chips to 500 degrees.
- irixusr 11y agoAnd it's not a very complicated circuit either.
- Johnny555 11y agoMuch easier than having to stay within easy reach of the computer's power switch at all times. Though I suspect that there are a very limited number of people in the world that actually face a threat of police coming into their home with a flask of liquid nitrogen to try to do a key recovery of latent data in RAM. This is probably the same set of people that are worried that someone will spend hundreds of thousands of dollars with an electron microscope to try to recover data from their hard drive. I'd bet that most people that think they are in this risk category do not have strong enough security practices to prevent data from being cracked by other means.
- mikeash 11y agoMight as well take this to the logical conclusion and have some thermite set to go off if anyone tampers with the case.
- jfindley 11y agoThere was an interesting experiment done on this at a DEFCON a few years back[1]. Thermite, even the more explosive copper-based variant, is pretty poor at destroying disk platters, sadly. Explosives or cutting equipment seem to be better, although the magnitude of the engineering challenge obviously increases. 1: https://www.youtube.com/watch?v=-bpX8YvNg6Y https://www.youtube.com/watch?v=-bpX8YvNg6Y
- mikeash 11y agoCool, I'll definitely have to watch that. Thanks for the link! Here's an alternate idea: rather than messing around with chemical explosives, how about filling the computer with poisonous snakes?
- Johnny555 11y ago